Corrosion of SS fixtures in water valve house
Corrosion of SS fixtures in water valve house
(OP)
Hi - we operate a number of valve houses for a large water transmission pipe system. Upgrades at one valve house included fixtures (wall vents, louvers, doors, railings, electrical enclosures) constructed of 316 stainless steel. All of these fixtures are showing some degree of corrosion (some heavy). The humidity of the air in the house is approximately 100%, and condensation is present on all surfaces. The water is from the treatment plant, so has significant chlorine concentrations (avg. dose at the plant is ~1.8 mg/l). Beyond pickling/passivation, is there any other treatment available?
Thanks much for any input!
Thanks much for any input!





RE: Corrosion of SS fixtures in water valve house
RE: Corrosion of SS fixtures in water valve house
Thanks again!
RE: Corrosion of SS fixtures in water valve house
316 does not corrode in the environment you describe unless something's wrong.
Check the sulfur level of the 316 from the source of the components. Specs allow up to 0.030%, but in actual practice it's bad news if the sulfur is above 0.005%.
If you clean the surfaces with acid you will remove any contaminants or exposed inclusions and solve your problem.
Blasting with glass beads will not help in any way.
RE: Corrosion of SS fixtures in water valve house
Be aware that some commercial cleaning solutions used in facilities contain chlorides or chlorites that can induce corrosion.
I doubt if sulfur level is the problem, although it is probably worth checking. Be aware that the very low sulfur level, <0.005%, will significantly decrease machinability and alter welding of the stainless.
RE: Corrosion of SS fixtures in water valve house
Thanks!
RE: Corrosion of SS fixtures in water valve house
RE: Corrosion of SS fixtures in water valve house
The myth of beneficial levels of sulfur comes from producers of welded stainless tubing who dope their stainless with large amounts of sulfur to increase their tube welding line speeds because they use TIG welding. They could achieve the same speed benefit by using laser welding and not ruining the corrosion resistance of the material.
RE: Corrosion of SS fixtures in water valve house
RE: Corrosion of SS fixtures in water valve house
RE: Corrosion of SS fixtures in water valve house
RE: Corrosion of SS fixtures in water valve house
RE: Corrosion of SS fixtures in water valve house
Definetly follow McQuire's and TEV's recommendations in reference to passivation and properly identifying the materials that were used and if this fail's to answer your problem, my next suggestion would be to look very closely at the environment these parts reside in to see if there is an additional chemical present you have yet to identify. Also examine the fasteners attaching these instruments to the structure. Are they also corroding? If not, while unlikely, you may be suffering galvanic corrossion.
Just my two cents worth and good luck.
RE: Corrosion of SS fixtures in water valve house
RE: Corrosion of SS fixtures in water valve house